Process of drying sand molds



Patented Mv. 29, lass.

N. SHAW.

PRUCESS 0F DRYING SAND MOLDS.

(Application led July 29, 1895.)

2 Sheets-Sheet l.

(No Model.)

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No. 6|5,|09. Patented Nov. 29,1898.4 N. SHAW.

PROCESS 0F DRYINGv SAND MOLDS.

(Application led July 29, 1895.)

2 Sheets-Sheet 2.

(N0 Model.)

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NOAH SHAW, OF EAU CLAIRE, WISCONSIN.

PROCESS oF DRYING SAND MoLDs.

SPECIFICATION forming part of Letters Patent N o. 61 5,109, dated November 29, 1898. Application filed July 29, 1895. Serial No. 557,453. (No model.)

To LZZ whom t may concern:

Be it known that I, NOAH SHAW, a citizen of the United States, residing at Eau Claire, in the county of Eau Claire and State of Wisconsin, have invented a new and useful Process of Drying Sand Molds, of which the following is a specification.

This invention relates to an improved process of drying sand and loam molds used in dry-sand castings.

The main and primary object of the invention is to provide a process of this character which shall insure the uniform, thorough, and speedy drying of sand molds for dry sand castings,whereby the many objectionable features of the ordinary method of drying such molds shall be overcome.

Heretofore dry-sand castings have been rendered very expensive to make by reason of eX- pensive appliances used in connection with drying of the sand molds, the liability to loss by defective molds, the defects in which remain undiscovered until the loss occurs, the excessive length of time required in drying the molds, and the cleaning thereof. In the first place in the processes heretofore carried out in dry-sand-casting work iron asks are invariably used, except for such molds as are made in the lloor or loam, where brickwork is substituted for the liask, and inthe carrying out of most of the ordinary processesA the molds are made in iron asks and finished with the ordinary blacking or Wash. The molds and flasks are then placed in ovens and subjected to heat from about twelve to forty-eight hours, according to the nature of the mold, and when sufliciently dried the molds and flasks are removed from the ovens, the cores put in place, and the molds closed before the molten metal is poured into the molds. In contradistinction to this process the present invention contemplates a process in the carrying out of which the molds are completely finished, the cores put in place while the molds are yet soft and not liable to crumble or crush, and the molds closed and kept closed until they are opened to remove the casting. This process or method not only effects a great saving of time in the preparation of the molds for the casting, but also insures perfect and complete molds, and therefore perfect castings.

In the uniform drying of the molds the process contemplated by the present invention possesses great advantages over the ordinary process of molding large castings. In such Work the castings are made in the floor or loam and thermolds are dried by the use of baskets of charcoal placed in different parts of the mold. Moreover, as the molds cannot be closed to retain the heat portions of the molds are not reached by the heat and are therefore improperly dried, While in addition to this other portions of the mold are burned A and the molds are lled with ashes and cinders, requiring much time and trouble in cleaning. In this connection it Will also be noted that molds which are dried in an oven are always left open and are filled with ashes and cinders, which must be cleaned out before the molds can be closed. All these disadvantages are overcome by the present invention in view of the fact that the molds can be completely finished and closed up ready for casting before the same are dried.

In the accomplishment of the objects sought for the invention essentially consists in forcing heated air under pressure into the molds after the same are finished and closed, thereby forcing the moisture in the sand of which the molds are composed outward through the pores of the sand, whereby the heated air which follows converts the moisture into steam or vapor and leaves the pores of the sand open for the free escape of the gases generated by the molten metal when poured into the mold.

' While it is the purpose of the present invention to have the heated air forced under pressure uniformly through the walls of the mold, still this is not always possible, as the Walls of some molds are of varying thickness and of different degrees of density, and for the same reason at times it might not be possible forvthe heated air to pass through all of the walls of the mold, although this would not interfere with the successful carrying out of the invention. Furthermore, while it is IOO mold be tightly closed. Therefore it will be understood that it is only essential to the success of the process that the mold be closed and that the fundamental feature of the invention consists in forcing heated air under pressure directly into the interior mold-cavity and from thence out through the pores in the walls of the mold.

To carry out the process referred to, different forms of apparatus may be employed; but the form of apparatus most convenient for the purpose is illustrated in thc drawings, in which- Figure 1 is a plan view of a mold-drying apparatus constructed to carry out the process contemplated by this invention. Fig. 2 is a side elevation, partly in section, of the same. Fig. 3 is a detail elevation showing the connection of the hot-air pipe with a mold for the purpose of drying the same. Fig. -t is a plan view of the under side of the cover or cope section of the mold and its inclosing flask. Fig. 5 is a vertical sectional View of a colnplete mold and its inclosing flask, showing the hot-air-pipe connection therewith. Fig. G is a top plan view of the mold with the cope or cover section removed.

Referring to the drawings, the numeral 1 designates a suitable furnace provided at one end with a fire-box 2 and with alongitudinal heating-chamber 3, in which is arranged a heating-cylinder 4, extending from end to end of the furnace. The heating-cylinder a is designed to be heated to a sufficient temperature by the heat within the furnace and is provided with opposite contracted ends 5, projected through the opposite ends of the furnace. One contracted end 5 of the heating-cylinder 4 has connected thereto one end of a cold-air pipe G, the other end of which is connected with an air-compressor 7, of an ordinary construction, and adapted to force air under pressure through the pipe G into and through the cylinder f1. The cold-air pipe G is provided at a suitable point with an ordinary safety-valve S and with a regulatingvalve 9 to control the supply of air from the compressor 7 to the heating-cylinder At the end opposite the connection of the pipe 6 therewith the heating-cylinder 4: has connected thereto one end of the hot-air pipe 10, which is placed below the molding-floor, as illustrated in Fig. 3 of the drawings.

The hot-air pipe 10 has suitably connected therewith at any suitable point an ordinary thermometer 11, diagram matically illustrated to indicate the temperature of the air, and at other points the pipe 10 has connected therewith the branch hot-air pipes 12, each of which pipes is adapted to bc fitted to the opening in the top of a finished and closed dry-sand mold 13 of the ordinary construction and which is placed on the molding-floor in the position in which it remains while the casting is being made. Each of the branch pipes 12 is provided at suitable points with an ordinary balland-socket joint 14, the construction of which is well known, so that such pipes can be readily adjusted to and away from the molds, and each of the pipes 12 is also provided with a regulating-valve 15 to regulate the pressure of air in the mold and also with a suitable prcssu re-ga ge 1 U, which indicates the pressure of air that is introduced into the mold for the purpose of quickly' drying t-he same.

A branch cold-air pipe 17 is connected with the pipe 10 and the pipe G and is provided with an ordinary cut-off valve 1S and an ordinary pressure-gage 19, similar to the gage 16. The function of the branch cold-air pipe 17 is to admit cold air directly into the pipe 10 in order to regulate or modify the temperature of the hot air forced through the pipe 10 and the branch-pipe connections 12 therewith, and by observing the thermometer 11 the valves and 18 can be so manipulated as to properly control the temperature of the hot air which is introduced into the molds.

The steps of the process will be readily apparent from the description of the apparatus preferably employed, for it will loe obvious that when a flask is closed with the finished mold therein it is simply necessary to connect one of the branch pipes 12 with the top opening of the mold. The air will then be forced under pressure from the compressor 7 into the heating -cylinder 4, where it is heated to the desired degree of temperature, and is still forced under pressure in its heated condition through the pipes 10 and 2 into the mold. As before stated,the heated air which passes into the mold under pressure works through the said mold outward and thoroughly and uniformly dries the mold in a very short space of time, ranging from five to thirty minutes, and as the hot air is forced through the mold the same dries up the moisture and leaves the pores open, through which the gases generated by the molten metal may freely escape.

lVhen the apparatus is first started, the hot air is admitted to the mold at about one-pound pressure; but as the mold dries the pressure is gradually increased by opening the valve 15 until the gage 1G shows the full pressure indicated by the gage 19, which is about fivepounds pressure to the square inch.

In connection with this process it will be obvious that wooden flasks may be employed in place of the heavyiron flasks, and, furthermore, it will be obvious that by introducing the heated air into the mold under pressure if there is any opening in the mold through which the molten metal could run out when the mold is being filled it is readily discov ered and accidents resulting from such defects are thereby obviated. This is a very important advantage, for the reason that large castings are frequently spoiled and sometimes entirely lost by the running out of the metal through defective openin gs in the mold which remain undiscovered.

The mold 13 is simply illustrated diagrammatically in Fig. 3 of the drawings to show IOC TOE

one of the ways in which the hot-air pipes may be arranged in connection therewith; but this mold is illustrated in detail in Figs. 4, 5, and 6 of the drawings. By reference to these gures of the drawings it will be observed that I have illustrated a form of mold having a rectangular sand body 14, inclosed within a correspondingly-shaped iron flask 15, provided in its sides, ends, and bottom with a plurality of vent-openings 16, which provide for the free passage of the heated air after being forced through the pores in the walls and bottom of the 1n old-body. In the form of mold illustrated the sand body 14 thereof is provided in its upper edge with a continuous annular vent-channel 17, with which communicate a plurality of vertical vent-holes 18, formed in the side and end walls of the sand body and subserving the usual function of providing for the escape of a portion'of the gas generated by the molten iron, as is always the practice both in dry and green sand mold work. The mold 13 is provided with the ordinary sand-cover section 19, packed within the upper or cope section 20 of the flask,which section of the flask is designed to be connected with the lower or drag section thereof in the usual manner. While a form of sand mold has been specically described and illustrated, it will of course be understood that the process may be effectively carried out in connection with any form of sand mold having a sand-cover section and inclosed within a perforate iiask, the perforations of which flask permit of the f ree escape from the mold of the heated air, and the 'cover-section of the mold is formed with a pipeopening 21 to snugly receive therein one end of the pipe connection 12 for delivering heated air into the interior of the finished inclosed mold for the purpose of drying the same in the manner hereinbefore fully explained.

From the foregoing it is thought that the details of the process herein set forth will be readily understood by those skilled in the art, and various changes in the minor details of carrying out the process may be resorted to without sacrificing any of the principles or advantages of the invention.

' Having thus described the invention, what is claimed, and desired to be secured by Letters Patent, is-

1. Aprocess for drying closed sand and loam molds, which consists in forcing heated air under pressure directly into the interior moldcavity, and from thence out through the pores in the walls of the mold.

2. A process for drying sand molds which consists in forcing heated air under pressure into and outward uniformly through all of the porous Walls of a finished and closed mold, substantially as described.

In testimony that I claim theforegoing as my own I have hereto affixed my signature in the presence of two witnesses.

NOAH SHAW.

Witnesses: s

IRVING D. HULL, W. W. JACKSON. 

